In general, a photolithography process comprises the steps of applying a photoresist composition on a substrate such as wafer, glass, ceramic, metal, and so on by a spin coating or a roller coating, forming a photoresist layer by heating and drying the applied photoresist composition, forming a photoresist pattern by exposing the photoresist layer to a exposure light of a predetermined pattern, optionally heating, and developing the exposed photoresist layer, and forming a semi-conductor element pattern by etching the substrate with the formed photoresist pattern as a mask. The photolithography process is widely used in production of a semi-conductor such as IC (Integrated Circuit), a LCD (Liquid Crystal Display), photography, and so on.
Due to the increasing demand for the highly integrated semi-conductor device, ArF excimer laser using an exposure light of wavelength of 193 nm, which is shorter than the wavelength (248 nm) of the KrF excimer laser, is used as the light source to increase the resolution of a photoresist pattern. In addition, F2 (157 nm) excimer laser, EUV (Extreme Ultra Violet), VUV (Vacuum Ultra Violet), E-beam, X-beam, ion beam, etc have been studied and developed as a light source of a lithography process. However, as being shorter the wavelength of the exposure light, optical interference of the light reflected from the etching layer of the semi-conductor substrate during the exposure process increases. In addition, due to undercutting, notching, etc., the photoresist pattern profile and the uniformity of thickness are deteriorated. To overcome these problems, the bottom anti-reflective coating (BARC) layer is conventionally formed between the etching layer and the photoresist layer to absorb the exposure light. The anti-reflective coating layer can be classified into the inorganic anti-reflective coating layer made of titanium, titanium dioxide, titanium nitride, chrome oxide, carbon, amorphous silicon, and so on, and the organic anti-reflective coating layer made of a polymer, which depends on the material for forming the anti-reflected coating layer. In comparison with the inorganic layer, the organic anti-reflective coating layer does not generally require complex and expensive apparatus such as a vacuum deposition equipment, a chemical vapor deposition (CVD) device, a sputter device and so on for forming the layer, and has a high absorptivity of a radioactive light, and is generally insoluble in a photoresist solvent. Also, small materials thereof does not diffuse from the anti-reflective coating layer into a photoresist layer during coating, heating, and drying the photoresist layer, and the organic anti-reflective coating layer has an excellent etch rate in a dry etch process of a photolithography process. But until now, the conventional composition for forming the organic anti-reflective coating layer is not satisfactory in its characteristics, such as the absorptivity of an exposure light.